$re = '%^/(?:\w+/?){0,2}$%m';
$str = '/
/abc
/def/
/ghi/jkl
/mno/pqr/
/stu/vwx/yz
/abc/def/ghi/jkl
/abc
/def/
/ghi/jkl
/mno/pqr/
/stu/vwx/
/abc/def/
/
/abc
/def/
/ghi/jkl
/mno/pqr/
/stu/vwx/yz
/abc/def/ghi/jkl';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php